Removing Dark Stains From Oiled Hardwood

Fill a glass microwave-safe jar with 1 pint of distilled water and add 3 to 4 tablespoons of oxalic acid. Stir the crystals and water with a spoon.

Microwave the jar on high for 30 seconds. Continue heating for 30-second intervals until the mixture is hot. You must keep the mixture hot for the entire process.

Use a paintbrush to apply the oxalic acid mixture to the dark stains. Continue until you have completely covered the discolorations. Leave the mixture on the oiled hardwood until it dries.

Continue applying the mixture and letting it dry until the dark stains are no longer present.

Mix 1 gallon of water with 3 ounces of borax. Moisten a cloth with the borax mixture and wipe the oiled hardwood to neutralize the bleaching action.

Remove the residue with a damp cloth and wipe dry with a soft towel.

Examine the oiled hardwood. If the oxalic acid makes the wood grain rise, sand the area lightly with a fine piece of sandpaper and stain the wood to match the surrounding area.